Method of destroying weeds



United States Patent 3,036,908 METHOD OF DESTRGYING WEEDS Fredo Giinther, Berlin-Steglitz, Germany, assignor t0 Schering A.G., Berlin, Germany, a corporation of Germany No Drawing. Filed Mar. 3, 1959, Ser. No. 796,758 Claims priority, application Germany Mar. 5, 1958 Claim. (Cl. 71--2.4)

This invention relates to weed killers, and particularly to weed killing agents comprising halogenand/or alkylsubstituted phenoxyacetic, phenoxypropionic and phenoxybutyric acids in combination with soluble phosphates.

It is known to utilize various chemical substances for the destruction of weeds prior to undertaking cultivation. And it has been proposed that such weed destruction be combined with fertilization so that the active weed killing agents are admixed with fertilizers in solid condition, whereby the fertilizer serves as a means of distributing the weed killer.

It was now found in accordance with this invention, that the growth herbicides used for weed destruction can be considerably increased in activity when applied to cultivated stands after the germinating of the cultivated plants and weeds by adding to the conventionally used aqueous sprays of growth herbicides a Water soluble salt of a phosphoric acid, in such an amount that about 0.251.5 kg. of P 0 are applied per hectare.

As growth herbicides there are suitable for this purpose halogenand/or alkyl-substituted phenoxyacetic phenoxypropionic acid or phenoxybutyric acids and their salts having the formula:

wherein R and R are members selected from the group consisting of hydrogen, halogen and alkyl, R is a mem ber selected from the group consisting of halogen and alkyl, M is a member selected from the group consisting of hydrogen, an alkali metal, and an aliphatic amine, and n is an integer from 1 to 3. These phenoxy acid derivatives may be used individually or in admixture with one another. Within the contemplation of this invention, other herbicides may also be-added to the weed killing compositions disclosed herein. Besides the free acids, there may be employed for this purpose the salts of said acids, such as the metal salts or the amine salts. Such metal salts may include, for example, the salts of the alkali metals, such as the sodium, potassium, and ammonium salts. Amine salts may also be used, such as, for example, the diethylamine salt, the diethanolamine salt, and the like.

As examples of ring-substituted phenoxy acids which may be employed in accordance with the present invention, there are mentioned:

4-monochlorphenoxyacetic acid 2-methyl-4-chlorphenoxyacetic acid 2,4-dichlorphenoxyacetic acid 3,4-dichlorphenoxyacetic acid 2,4,5-trichlorphenoxyacetic acid 4-monochlorphenoxypropionic acid 2-methyl-4-chlorphenoxypropionic acid 2,4-dichlorphenoxypropionic acid 3,4-dichlorphenoxypropionic acid 2,4,5 -trichlorphenoxypropionic acid 4-monochlorphenoxybutyric acid 2-methyl-4-chlorphenoxybutyric acid 3,4-dichlorphenoxybutyric acid 2,4-dichlorphenoxybutyric acid 2,4,S-trichlorphenoxybutyric acid 35 part of KH PO 5 tained surprisingly and unexpectedly a much more intense destruction of weeds than without such an addition. Suitable water soluble salts include the salts of orthophosphoric acid and pyrosphoric acid. The water soluble phosphates which are advantageously employed include for example, the alkali metal salts of the aforementioned phosphoric acids such asthe sodium, potassium, and ammonium salts, but also the calcium salts such as for example Ca(H PO In accordance with the invention, the phosphates are added to the spraying compositions in such low concentrations that they produce no fertilizing eifect whatever. In general the amount of phosphate added need not exv.ceed about 5.0 kg. of P 0 per hectare, but a significant augmentation of the herbicidal action is attained even with amounts as low as 0.251.5 kg. of P 0 per hectare,

as illustrated in the tests described below.

The necessary concentration of the aqueous compositions depends largely on the manner in which they are applied to the cultures, and on the cultures treated.

The concentration must be higher for instance in solution applied by plane than in those applied on the ground by atomizing or by spraying. When a spraying composition of 400 l. is applied to one hectare the preferred concentrations are about 0.125 to 0.5% of growth herbicide'and 0.125 to 0.5% of the water soluble phosphate.

l n the following there are given only for illustration purpose some examples of spraying compositions.

(1) Two parts of the potassium salt of chloromethyl phenoxypropionic acid are mixed thoroughly with one Three kg. of this product are dissolved in 400 l. of water and this solution is sprayed on one hectare of land carrying cereal crops.

(2) One part of the sodium salt of methylchlorophenoxypropionic acid is mixed thoroughly with 1 part of a 0 mixture of 90% N32H2P207 and 10% Na P O- Three kg. of this product dissolved in 4001. of water are applied to one hectare. I

(3) Three parts of the diethylamine salt'of 2,4,5-trichlorophenoxypropionic acid and 1 part of potassium 5 MCPA are mixed thoroughly with two parts of Na P O- dissolved and applied as indicated above under 2.

It has been further found, in accordance with this invention, that the spraying compositions should advantageously possesses a pH of 6 or more. This condition has the 0 further advantage that the growth materials are better soluble, for in more strongly acid media a light turbidity could occur owing to precipitated material.

It was demonstrated, as shown in Example 4 below, that in the case of adequately fertilized soils, and even 5 in the case of strongly overfertilized soils, a further significant increase in weed killing action was obtained by the fj addition of phosphates to the spraying composition in accordance with the present invention. That a genuine jsynergistic increase in activity is taking place is proved by e the fact that upon spraying of phosphate alone no damage Not any kind to the plants was observed, cf. Example 7.

In accordance with the present invention, therefore,

there is provided a process which is based upon an entirely novel type of action, and one which was not provided by any method known heretofore.

The surprising and unexpected results obtainable by the composition and process of this invention are demonstrated by the following examples, but the invention is not to be regarded as limited thereto.

In the examples, the increase in weed killing activity was demonstrated in greenhouse tests at various tempera- 4 2,4,5-T-Na--sodium salt of 2,4,S-trichlorphenoxyacetic acid MCPP-amin-diethanolamine salt of methyichlorphenoxypropionic acid tures using dicotyledonous plants of five different families, whereby the general applicability of the activity increase was proved. These plants included the following:

z iiig i i t z ih Stellarla medm 5 MC -Na-sdium salt of methylchlorphenoxybuty- Ageratum mexicanum T10 ci EXAMPLE 1 Centaurea cyanus Galinsoga parviflora Cruciferae: Sinapis alba Scrophulariaceae: Antirrhinum majus Greenhouse tests-The phytotoxicity of various herbicides with addition of various amounts of phosphates is shown in the following Table l. The amount applied was Solanaceae: Solanum lycopersicum 1,000 liters per hectare.

Table 1 kg./ha. KIIZPOJ Average Tempera- Plant Herbicide tnrc C 0.), 0 0.5 1 2 3 during test period I-Sinapia aZba(4-leafstago). MSTPHZK 4.1 5.0 5.0 5.0 5.0 5.3 21.3

'2. a. II-Stellaria media(10-1eat-stage). MzClPPlgK 4.6 6.3 6.6 6.7 6.7 6.7 21.2

rg. a. III-Centaurea cyanus (4-leai- MCPP-K 3.6 4.4 4.6 4.8 4.6 20.8

stage). 1 kgJha.

kgJha. N84P207 IV-Atriplez patuZum+Galinaoga MCPP-K 3.4 6.15 6.15 6.6 6.65 6.65 20.8

parviflora-l-Stcllaria media. 1 kgJha.

Example 3 demonstrates that the weed killing activity EXAMPLE 2 increase occurs in open fields as well, and without any Greenhouse tests.-These tests demonstrate the phytoadverse efiect upon selectivity. toxicity of various growth herbicides to various plants at The toxicity values given in the examples represent various temperatures upon spraying with 1,000 liters per average values from a large number of evaluations durhectare. Each toxicity value is the average value for 8 ing the test period. The evaluations are in terms of evaluations during a test period of 4 weeks. Drepresents a scale ranging from 0 (plants undamaged) to 10 (plants the average difference in toxicity value for a given growth dead). In the tables given below the abbreviations used herbicide between its action with and without potassium to denote the compounds in question have the following phosphate (KI-1 1 0 upon the test plants at the test meanings: temperatures. The results of these tests are shown in Abbreviation? Table 2 below, in which the following abbreviations are MCPA-K-potassium salt of methylchlorphenoxyused to denote the test Plants:

acetic acid Age.=Ageratum mexicanum Ant.=Antirrhinum majus Sin.=Sinapis alba Sol.=S0lanum lycopersicum MOPP-K-potassium salt of methylchlorphenoxypropionic acid 2,4-D-Na-sodium salt of 2,4-dichlorphenoxyacetic acid Ste.=Stellaria media Table 2 Agent, kg./ha. MC1;AK 2, 4-13-Na 2, 4, 5TNa M CPPBAmin MCPB-gia KHaPO4, kgJha. 0 1 0 l 0 1 0 1 0 1 Toxicity Values, 0.:

Age;

1 Not tested.

As demonstrated by the data in the foregoing tables the increase in herbicidal action is especially large in the case of the substituted phenoxypropionic acid and phenoxybutyric acid compositions of the present invention.

EXAMPLE 3 (a) Open field test on yellow oats (Brunotte).Sowings were made on March 31, 1958. Spraying on May 5, 1958, with 600 liters per hectare. Parcels almost exclusively overgrown by Sinapis alba,'Papaver dubium; Chenopodium spec., Galin-soga parviflora and Stelluria media.

Herbicidal effect on weeds on June 13, 1958:

Table 3 MOPA-K, Na P QO kgJha. Tox. kg./ha. kg./ha. Val.

MCPP-K, KHZPO4, kg.[ha.

kgJha.

(b) Open field tesron summer wheat-A test carried out with potassium methylehorphenoxypropionate and potassium dihydrogen phosphate as shown-in Table 4. The difference in grain yield between the last two tests is within the limits of statistical variation.

'Table 4 Toxicity MCPP-K KHgPQ Value (4 Grain Yield, kg/ha. weeks after Percent treatment) Untreated 100 3 8 111.5 2 1 8 114 EXAMPLE 4 Greenhouse text.-The phytotoxicity was determined of the sodium salt of trichlorphenoxyacetic acid (2,4,5-T-Na) to Solanum lycopersicum, sprayed at the 4-1eaf stage with 1,000 liters per hectare, at an average temperature of 20.2 C. during the test period. The toxicity data given in Table represent the average of 5 evaluations during the 10 day test period.

Table 5 6 Table 6 Toxicity values MCPA-K, 1 kg./ha. 4.0

MCPA-K, 1 kg./ha. and prim. potassium orthophosphate, 1 kg./ha 4.8 MCPA-K, 1 kg./ha. and tetrapotassium pyrophosphate, 1 kg. ha. MCPA-K, 1 kg./ha. and disodium pyrophosphate,

1 kg./ha. 5.0 MCPA-K, 1 kg./ ha. and tetrasodium pyrophosphate,

1 kg./ha. 4.8 MCPA-Na, 1.15 kg./ha. 4.25 MOPA-Na, 1.15 kg./ha.' and prim. sodium orthophosphate, 1 kg./ha. 5.1 MCPA-Na, 1.15 kg./ha. and prim. sodium orthophosphate, 10 kg./ha 4.8 MCPA-Na, 1.15 kg./ha. and prim. potassium orthophosphate, 1 kg./ha. 5.25 MCPA-Na, 1.15 kg./ha. and prim. potassium orthophosphate, 10 kgL/ha. 4.8

7 EXAMPLE 6 Greenhouse test.-The phytotoxicity was determined of the diethanolarnine salt of methylchlorphenoxypropionic acid (MCPP-Amin) to Antirrh'inum majus and Ageratum maxicanum, sprayed at the 4-leaf stage with 1,000 liters per hectare, average temperature during the test period Greenhouse test.-Ageratum mexicanum, Antirrhinum mujus, Galinsoga parviflora, and Stellaria media were sprayed with 1 kg. of primary potassium orthophosphate Spraying 0.5 kg./ha. 2,4,5-T-Na Cultivation more than 2 days before Addition of KHzP O4 2 days before spraylngspraying Size of amountof phosphorus calcul. as P205 0 I fould amount of fould amount of compl.fertilization compl.fertilization Cultivation in phosphorus-poor soil without additional fertilization. 1. 6 2. 5 3. l 3. 3 5. 8 6.0 6.0 6. 1 Cultivation in phosphorus-poor soil +several complete fertilizationa... 1. 9 2. 3 2. 4 2. 1 5. 8 6. 0 6. 0 5. 8

EXAMPLE 5 per hectare. Noneof the plants showed any 1n ury whatever.

EXAMPLE 8 (n) The phytotoxicity was determined of the potassium salt of MCPP to Galiumi aparine, sprayed at the stage of 3 to 4 leave-whorls with 1000 liters per hectare, average temperature during the test period of 14 days 15 C., the toxicity data given in Table 8 represent the average of 4 evaluations during the test period of 14 days.

Table 8 MCPP-K, kgjha. KH2PO4, kgJha. Tox. Val.

(b) The phytotoxicity was determined of the potassium salt of MCPP to Galiuma aparine, sprayed at the stage of 6 to 7 leave-whorls with 1000 liters per hectare, the toxicity data given in Table 9 represent the evaluation after the test period of 32 days.

Table 9 Tox. Val.

MCPP-K, kgJha.

EXAMPLE 9 Table 10 2,4-DB-Na, kgJha. Na4P207, Tox. Val.

kgJha,

EXAMPLE 10 Table 11 Tox. Val. Phosphate, kgjha.

MCPP-K, kgJha.

Centaurea Sinapis Stellaria This test demonstrates that there is no remarkable difference in the eifect of phosphates of acid or basic action.

EXAMPLE 11 The phytotoxicity was determined of combinations of difierent herbicides sprayed to Centaurea cyanas in the 4leaf stage and Matricaria chamomilla in the 14-leaf stage with 1000 liters per hectare. The toxicity data given in Table 12 represent the average of 4 evaluations 1 Stellarta media in preflowering stage.

during the test period of 12 days (Centaur-ea cyanus) and 6 evaluations during 18 days (Matricaria chamomz'lla).

Table 12 Tox. Val. 50% MCPA-K, 50% 2,4-D-K, NailzOv,

kgJha. kgJha.

Ceutaurca Matricaria 75% CMPP-K, 25% MCPA-K 25% MCPA-K 2 3.75 3 5 2 l 7.75 4 5 EXAMPLE 12 The phytotoxicity was determined of the diethylamine salt of 2,4,S-trichlorophenoxypropionic acid (2,4,5-TP- amine) sprayed to Galeopsis tetrahit in the 8 leaf stage and Stellarz'a media in the stage before blooming with 1000 liters per hectare. The toxicity data represent the evaluation after 24 hours after spraying.

Table 13 Tox. Val. 2,4,5-TP amlne,kg.lha. NE12H2P107,

kgJha,

Galeopis Stellarla Rr-Qowmncooir wherein R is selected from the group consisting of H, Cl, and CH R is Cl, R is selected from the group consisting of H and Cl, M is selected from the group consisting of H, an alkali metal, an alkylarnine, and an alkanolamine, and n is an integer from 1 to 3, and from about 8 to about 91 percent by weight of a water soluble salt of a phosphoric acid, said salt being selected from the group consisting of the alkali metal salts, alkaline earth metal salts, and ammonium salt, in an amount such that about 0.25 to 1.5 kg. of P 0 are applied per hectare.

References Cited in the file of this patent UNITED STATES PATENTS 2,326,471 Lontz Aug. 10, 1943 2,444,905 Sexton July 13, 1948 2,453,983 Sexton Nov. 16, 1948 2,709,648 Ryker May 31, 1955 2,768,889 Tworney et a1 Oct. 30, 1956 2,792,295 Wright May 14, 1957 FOREIGN PATENTS 152,955 Australia Aug. 26, 1952 212,921 Australia Feb. 5, 19 58 

